--- a/gfx/thebes/gfxPlatform.cpp
+++ b/gfx/thebes/gfxPlatform.cpp
@@ -2152,40 +2152,50 @@ gfxPlatform::UseProgressivePaint()
 }
 
 /*static*/ bool
 gfxPlatform::PerfWarnings()
 {
   return gfxPrefs::PerfWarnings();
 }
 
-void
-gfxPlatform::GetAcceleratedCompositorBackends(nsTArray<LayersBackend>& aBackends)
+static inline bool
+AllowOpenGL(bool* aWhitelisted)
 {
-  // Being whitelisted is not enough to accelerate, but not being whitelisted is
-  // enough not to:
-  bool whitelisted = false;
-
   nsCOMPtr<nsIGfxInfo> gfxInfo = do_GetService("@mozilla.org/gfx/info;1");
   if (gfxInfo) {
     // bug 655578: on X11 at least, we must always call GetData (even if we don't need that information)
     // as that's what causes GfxInfo initialization which kills the zombie 'glxtest' process.
     // initially we relied on the fact that GetFeatureStatus calls GetData for us, but bug 681026 showed
     // that assumption to be unsafe.
     gfxInfo->GetData();
 
     int32_t status;
     if (NS_SUCCEEDED(gfxInfo->GetFeatureStatus(nsIGfxInfo::FEATURE_OPENGL_LAYERS, &status))) {
       if (status == nsIGfxInfo::FEATURE_STATUS_OK) {
-        aBackends.AppendElement(LayersBackend::LAYERS_OPENGL);
-        whitelisted = true;
+        *aWhitelisted = true;
+        return true;
       }
     }
   }
 
+  return gfxPrefs::LayersAccelerationForceEnabled();
+}
+
+void
+gfxPlatform::GetAcceleratedCompositorBackends(nsTArray<LayersBackend>& aBackends)
+{
+  // Being whitelisted is not enough to accelerate, but not being whitelisted is
+  // enough not to:
+  bool whitelisted = false;
+
+  if (AllowOpenGL(&whitelisted)) {
+    aBackends.AppendElement(LayersBackend::LAYERS_OPENGL);
+  }
+
   if (!whitelisted) {
     static int tell_me_once = 0;
     if (!tell_me_once) {
       NS_WARNING("OpenGL-accelerated layers are not supported on this system");
       tell_me_once = 1;
     }
 #ifdef MOZ_WIDGET_ANDROID
     NS_RUNTIMEABORT("OpenGL-accelerated layers are a hard requirement on this platform. "

--- a/gfx/thebes/gfxWindowsPlatform.cpp
+++ b/gfx/thebes/gfxWindowsPlatform.cpp
@@ -1962,16 +1962,20 @@ gfxWindowsPlatform::CheckD3D11Support(bo
     *aCanUseHardware = !GetParentDevicePrefs().useD3D11WARP();
     return FeatureStatus::Available;
   }
 
   if (gfxPrefs::LayersD3D11ForceWARP()) {
     *aCanUseHardware = false;
     return FeatureStatus::Available;
   }
+  if (gfxPrefs::LayersAccelerationForceEnabled()) {
+    *aCanUseHardware = true;
+    return FeatureStatus::Available;
+  }
 
   if (nsCOMPtr<nsIGfxInfo> gfxInfo = services::GetGfxInfo()) {
     int32_t status;
     if (NS_SUCCEEDED(gfxInfo->GetFeatureStatus(nsIGfxInfo::FEATURE_DIRECT3D_11_LAYERS, &status))) {
       if (status != nsIGfxInfo::FEATURE_STATUS_OK) {
         if (CanUseWARP()) {
           *aCanUseHardware = false;
           return FeatureStatus::Available;